February 25/Food & Farm Week -- According to a study from Guelph, Canada, "Lycopene can undergo degradation via isomerization and oxidation during processing and storage. These degradative reactions affect its bioactivity and health benefit functionality."
"Degradation kinetics and isomerization of lycopene in water- and oil-based tomato model systems were investigated as a function of thermal treatments and light irradiation. Results showed that 80 and 100 degrees C heating favoured the stability of lycopene in oil-based tomato products. The high heating temperatures (120 and 140 degrees C) increased isomerization of lycopene and resulting in degradation of total lycopene and cis-isomers in both water- and oil-based tomato products. However, the levels of degradation of total lycopene contents and cis-isomers were greater in water-based samples than in oil-based model systems under different treatments. Heat and light both promoted lycopene isomerization of the all-trans form to the cis-isomers and further oxidation of cis-isomers. The major effect of thermal degradation and photosensitized oxidation was a significant decrease in the total lycopene content, especially the content of cis-isomers," wrote J.C. Chen and colleagues.
The researchers concluded, "These research results could be useful in assisting industry to improve processing technology and to improve the nutritional value and health-benefits of tomato-based foods."
Chen and colleagues published their study in Lwt - Food Science and Technology ("Comparison of lycopene stability in water- and oil-based food model systems under thermal- and light-irradiation treatments." Lwt - Food Science and Technology, 2009;42(3):740-747).
For more information, contact J. Shi, Agriculture & Agri Food Canada, Guelph Food Research Center, 93 Stone Rd. W, Guelph, ON N1G 5C9, Canada.
From the February 16, 2009, Prepared Foods E-dition